Portable battery tester with means to simulate normal operating drain conditions

ABSTRACT

A portable battery tester with a meter to measure the battery voltage through a series resistor adjusted to limit the current to the meter to the operating range of the meter, and with variable shunt resistors adjustable to a value that will simulate the load conditions to which the battery is to be applied, to simulate the current drain for that usage.

United States Patent Mallory [54] PORTABLE BATTERY TESTER WITH MEANS TOSIMULATE NORMAL OPERATING DRAIN CONDITIONS [72] Inventor: 73 Assignee:

Henry Rogers Mallory, Greenwich, Conn. P. R. Mallory & Co., Inc.,Indianapolis, Ind.

221 Filed: June 11, 1970 21 Appl.No.: 45,524

[56] References Cited UNITED STATES PATENTS 2,229,009 1/1941 Berry.,,...324/ 29.s

METER 1151 3,656,061 1451 Apr. 11,1972

2,225,051 A 12/1940 I-Ieyer ..324/29.5 2,540,225 2/1951 Wengel..324/29.5 X 2,675,522 4/1954 Godshalk ..324/29.5

Primary ExqminerRudolph V. Rolinec Assistant Examiner-R. J. CorcoranAtt0rneyRobert Levine [57] ABSTRACT A portable battery tester with ameter to measure the battery voltage through a series resistor adjustedto limit the current to the meter to the operating range of the meter,and with variable shunt resistors adjustable to a value that willsimulate the load conditions to which the battery is to be applied, tosimulate the current drain for that usage.

4 Claims, 6 Drawing Figures PATENTEUAFR 1 1 I972 SHEET 1 OF 2PATENTEDAPR 1 1 m2 SHEET 2 BF 2 ATTORNEY DESCRIPTION OF THE INVENTIONThis invention relates to a portable battery tester for testingbatteries of various voltages, under current drain conditions whichsimulate and correspond to the operating conditions of the intendedapplication and use of the battery. The conventional battery testersgenerally test batteries solely according to the voltage of the battery,but do not operate the battery tester to provide for a test that willconsider also the service conditions which the battery will encounterand be exposed IO.

The object of this invention is to provide a battery tester that willtest batteries of various voltages, under current drain conditions thatsimulate the load conditions under which the battery will be used inequipment in the field.

The novel feature in this new all purpose battery tester provides twoload simulating shunt rheostats, in addition to, a conventional seriesvariable resistor, all of which are coupled to a rotary battery voltagerange changing switch. The series resistor and the two shunt rheostatsare connected to a three position auxiliary slide switch which selectsand establishes the approximate current drain to simulate the useconditions for which the battery under test is intended. The threeposition slide switch provides for testing for three kinds of currentdrain, namely, light drain, medium drain and heavy drain. Light drain isused for camera electric eye, clock, or hearing aids. Medium drain isused for radio, tape recorder or electronic equipment. Heavy drain isused for flashlight, lantern, photoflash, motor drive, or television.The approximate current loading in the tester for batteries containingone through ten cells shown for purposes of demonstration, is l Amilliamperes for light drain; milliamperes for medium drain; and lampere for heavy drain. The 15 and 30 cell battery position of thetester conventionally tests batteries only under the l lmilliamperelight drain load and in those positions the shunt rheostats are open.

In operation the voltage rotary switch is set to vary the number ofseries resistors to match the voltage rating of the battery under test.The drain slide switch is then set to light drain, medium drain or heavydrain, which adjusts the shunt resistors to values corresponding to theconditions in the intended application for which the battery will beused. The battery is then tested in the conventional manner byconnecting the positive terminal of the battery to the positive lead ofthe tester, and the negative battery terminal to the negative lead ofthe tester. A serrated metal button at positive potential is included onthe face of the tester to facilitate testing of small batteries withterminals at opposite ends such as AAA, AA, C and D cells, etc. Twoflexible leads are provided for testing batteries with both terminals atone end.

The general construction of the battery, and the arrangements of theseveral components thereof, as well as the internal circuit diagram forthe arrangement of the resistances between the indicating meter and theinput terminals to the battery tester, are all described in more detailin the following specification, taken together with the accompanyingdrawings, in which FIG. 1 is a front elevational view of the testershowing the meter, an operating knob for the voltage setting switch, andshowing an auxiliary slide switch for the rheostate for drainconditions; i

FIG. 2 is a rear elevational view of the tester shown in FIG. 1; and

FIG. 3 is a schematic circuit diagram of the battery tester showing theindicating meter and the arrangement of the adjustable resistancesdisposed between the terminals to the tester; and

FIGS. 4a, 4b, and 4c are a set of three circuit diagrams for one voltagesetting of the tester.

As shown in FIG. 1, a battery tester 10, as viewed from the front,comprises a housing 12 having a front panel 14 on meter and the inputwhich are supported an indicating meter 16, a knob 18 for operating theswitch and two ganged rheostats, seen in FIGS. 2

and 3, with the switch knob 18 movable to various positions indicated,corresponding to the number of cells and the voltage of a battery to betested. The front panel 14 also supports a three-position servicecondition switch 20 which is movable to an intermediate position and toeither extreme position according to-the nature of the service to whichthe battery will be subjected in use. The three positions as furtherindicated by three legends are represented by a button 22, and legendfor light drain, by a button 24 and legend for an intermediate positionlabeled medium drain, and by a button 26 and legend heavy' drain, toindicate the right hand position to which switch 20 will be moved forbatteries to be subjected to such service test.

For further simplifying the testing of an external battery, a button 28is provided near the bottom border of the front panel 14 to permit anoutside battery, whose voltage terminals of opposite polarity are onopposite ends of the battery, to be seated with one terminal on thatbutton 28, which is connected internally to a positive input terminal ofthe internal wiring.

Two other input terminals are provided by two external prong pointterminals 30 and 32, supportedin insulating cylinders 34 and 36,respectively, and connected to the internal circuit wiring throughflexible leads 38 and 40, respectively, to permit the two outer prongterminals 30 and 32 to be connected to the terminals of an externalbattery that are mounted in positions to make it inconvenient to placethe positive terminal of the battery on the button 28 on the front panelof the tester.

The indicating meter 16 is provided with two scales 16A and 168 on whicha movable pointer 16-? indicates the condition of the battery beingtested, as being used up and to be replaced, or as being still good forfurther use, according to the voltage of the battery under test andaccording to the current capacity still available.

As shown in FIG. 2, as a rear view of the panel 14, the meter 16 isanchored in place by two suitable anchoring studs and nuts 42 and 44, tohold the meter against displacement on and 14 which may be of aluminum,with the holes 50 and 52 large enough to assure no contact with themeter terminals 46 and 48.

The ganged switch 56 and the resistors associated therewith andconnected thereto are shown directly beneath the meter and directlybehind the operating switch handle 18 shown on the front of the panel inFIG. 1. Directly under the ganged switch 56 is a service type switch 58,which may be shifted to anyone of the three positions indicated in thefront view in FIG. 1, to provide the appropriate circuitry in the gangedswitch 56 for an appropriate reading on the meter correspond ing to thetype of service to which the battery under test will be subjected duringservice.

The two battery leads 38 and 40 shown in FIG. I are again shown in FIG.2 as extending through an opening 39 in which an insulating grommet 41is anchored to hold the battery leads 38 and 40 against undesirablemovement or displacement. Those two leads are shown connected toappropriate terminals which will be more clearly identified in thecomplete circuit diagram shown in FIG. 3.

As shown in FIG. 3, the meter 16 is shown provided with two terminals 60and 62 which are connected through suitable conductors to the two outerprong terminals 30 and 32 at the ends of the flexible leads of theinstrument shown in FIGS. 1 and 2. The auxiliary positive terminal 28,connected to the same conductor as the positive terminal 32, is alsoshown in FIG. 3 as well as in FIG. I, to indicate the resting terminalon which one end of an outside battery or cell may be seated while theother terminal of the battery or cell may be connected to the negativeelectrode 30 of the terminal lead 38 in FIG. 1.

As shown inFlG. 3, three rheostats 64, 66 and 68 are respectivelyprovided with wiping contact terminals 64-A, 66- A and 68-A which areall mechanically mounted for simultaneous movement by a single shaft 70,indicated by the broken lines joining the three wiping contacts 64-A,66-A and 68-A. The operating shaft 70 is arranged to be rotated by theknob 18 shown in FIG. 1, and schematically indicated in MG. 3.

The incremental resistance switch 64 is provided with a series ofterminals respectively corresponding to the voltage of an externalbattery that is to be tested, and connected to the resistors K which arealso in series. The voltages are shown increasing in increments of 1.5volts, to correspond to the general average voltage of a commercial unitcell. Thus, the

-.voltages are indicated from 1.5 volts of a single cell battery, up

to 15.0 volts for a ten-cell battery, with the extreme two terminalpoints indicated for use to measure the condition of a battery of 22.5volts or one of 45.0 volts. The resistors series.

connected between the successive terminals are indicated, with thedesignation 1K representing one kilohm, of 1,000 ohms, so that l kilohmresistance is shown between'each of the successive terminal points fromthe first marked 1.5 volts to the one marked 15.0 volts. The resistorsto the final two terminals are indicated as 5.1 kilohms and kilohms,respectively. The variable shunt resistor 66 is shown as a continuousrheostat, and varies as indicated on the diagram from 0 to 13.5 ohms,and is connected in series with a fixed resistor 72 having the indicatedvalue of 1.5 ohms.

The variable shunt resistor 68 is shown as a continuous rheostat with amovable contact 68-a movable from a point of 0 ohms to a final value of720 ohms, and that rheostat 68 is connected in series with a fixedresistor 74 having a value of 80 ohms.

The three switches 64-A, 66-A and 68-A are ganged on a single operatingshaft 70, as shown by the broken line in FIG. 3, for simultaneousoperation by the operating knob 18. That operation sets the tester forthe value of the battery that is to be connected to the two terminals 30and 32 for testing. In addition, however, it is desired to obtain a testreading that will demonstrate the condition of the battery for thespecific use for which it is to be put in service. For that purpose, theswitch shown in FIG. 1 is now indicated in FIG. 3 as embodying athree-position slide switch 76, which is movable from an extremeright-hand position shown marked LD, representing the condition LowDrain, to a mid-position represented by the letters MD representingMedium Drain, and is movable to a third position at the extreme left,represented by the letters l-ID meaning High Drain.

The two rheostat resistor circuits 66 and 68 are provided for serviceonly over the range from 1.5 volts to 15.0 volts, of the gangedswitching arrangement. When the switch is set on the 22.5 volt or on the450 volt position, the two rheostats 66 and 68 are disconnected from thecircuit.

Thus it will be seen that the variable resistor 64 with its terminalsrepresents a series resistor for connection in the positive conductorbetween the positive input terminal 32, or the corresponding button 28,and the positive terminal 62 on the meter.

The two rheostats 66 and 68, however, are disposed to'function asparallel shunts between the positive input terminal 32 and the negativeinput terminal 30, to provide a circuit to measure a voltage dropcorresponding to the battery voltage.

In order to illustrate simply, the efiect of the switch 20, theconditions representative of the three positions of the servicecondition switch 20 are shown in FIG. 4, a, b and c, for a battery ofthree cells representing a voltage of about 4.5 across the battery to betested. As shown in FIG. 3 and FIG. 4 a with the blade 76 of the serviceswitch 20 of FIG. 3 in low drain position, between terminals a and b ofswitch 20, the meter l6 is connected to an external battery 65 to betested with the wiper 64-A on the 4.5 volt terminal so that the seriesresistance 64 includes 2 kilohms in series circuit between the meter 16and the test battery 65. For that low drain setting, neither shuntrheostat 66 or 68 is connected in circuit.

For thatsame setting of the switch for thebattery of 4.5 volts, when itis of such type as to provide a medium drain, the blade 76 will be movedto bridge the two mid terminals 20-h and 20-c to connect rheostat 68 inshunt circuit across the two conductors 38 and 40, at the inputterminals. In this circuit arrangement the 4.5 volts of the batteryestablishes a voltage drop within range close to or at 4.5 volts acrossthe circuit including the fixed resistor 74 and the variable rheostat68. The resistance introduced by the rheostat 68 corresponds to a loadto which the battery will be normally subjected during service, and themeter 16 thus measures the voltage drop across the load and thusprovides an indication of the battery condition as being up to voltageor below voltage suitable for serving such load.

FIG. 8-0 shows the circuit arrangement for high drain. The resistanceterminal 64-11 is on the 4.5 volt terminal of the rheostat 64. Therheostat 68 is now disconnected, and rheostat 66 is now connected inshunt between the two conductors 38 and 40 by blade 76 of switch 20 oncontacts 20-0 and 20-11. For the position now being considered, theshunt circuit includes the 1.50 ohm resistor 72 and three ohms of therheostat 66, making a total shunt resistance of 4.5 ohms, that providesa heavy drain of one ampere on the battery, with the l ampere throughthe shunt rheostat 66 providing a voltage drop in the range approaching4.5 volts across the rheostat circuit 66, so the voltage on the meterwill correspond to the voltage of the battery and thus indicate whetherit is sufficient to provide the current capacity needed for service ofthat heavy drain application.

With each adjustment of the ganged rheostat switch to a differentposition to accommodate the testing of a battery of a different voltage,the appropriate resistors are included in the series circuit, and in theshunt circuit, to keep the current through the meter within theoperating range of the meter, so that the indication on the scale of themeter will indicate whether the voltage of the battery being testedshows a condition in the battery that is adequate for the service forwhich it is to applied or whether the battery is no longer fit forservice and should be replaced. Thus, as shown on the face of meter 16,the voltage of the battery being tested will be shown to be low andunsuited for use, or will be shown to be high and adequate for servicein its intended field of use.

The invention is not limited to any specific type of meter or switcharrangement since various modifications may be made in the type of meterand in the values of the resistors and rheostats with the provisionhowever that the external resistors, particularly the series resistors,should be such, in respect to the resistance of the meter coil, that thecurrent through the meter will be kept within the range for which it isdesigned, to provide a pointer actuation to indicate the voltage of thebattery being tested as being at a certain value within a selectedrange.

Thus such modifications may be made within the spirit and scope of theinvention without departing from the spirit and scope of the claimsherein. A

What is claimed is:

l. A multiple level drain tester for batteries containing a variablenumber of cells, comprising a. an indicating meter having an indicatingpointer, at least one scale, actuating means for said pointer,responsive to the current from the battery to be tested and meterterminals;

b. battery terminals to be connected to said battery c. resistance meansserially connected between said meter terminals and said batteryterminals, comprising incrementally variable series resistance meansproportioned to the number of cells in said battery.

d. first switch means for adjusting the resistance increments of saidseries resistance in proportion to the number of cells in the battery e.at least two variable shunt resistance means connected across saidbattery and meter terminals for simulating test load drain conditions,each of said shunt means connected with said first switch means andsimultaneously actuated thereby for proportionally varying the shuntresistance according to said cell number and f. second switch means fordisconnecting all of said shunt means but the one simulating the draincondition being tested on said battery.

2. A battery tester, according to claim 1 in which said meter actuatingmeans is anactuating coil and said incremental se ries resistance meansis variable to include an effective resistance value in.said meter coilcircuitcorresponding to the number of unit cells in the battery beingtested.

3. A battery tester, according to claim I in which said two

1. A multiple level drain tester for batteries containing a variablenumber of cells, comprising a. an indicating meter having an indicatingpointer, at least one scale, actuating means for said pointer,responsive to the current from the battery to be tested and meterterminals; b. battery terminals to be connected to said battery c.resistance means serially connected between said meter terminals andsaid battery terminals, comprising incrementally variable seriesresistance means proportioned to the number of cells in said battery. d.first switch means for adjusting the resistance increments of saidseries resistance in proportion to the number of cells in the battery e.at least two variable shunt resistance means connected across saidbattery and meter terminals for simulating test load drain conditions,each of said shunt means connected with said first switch means andsimultaneously actuated thereby for proportionally varying the shuntresistance according to said cell number and f. second switch means fordisconnecting all of said shunt means but the one simulating the draincondition being tested on said battery.
 2. A battery tester, accordingto claim 1 in which said meter actuating means is an actuating coil andsaid incremental series resistance means is variable to include aneffective resistance value in said meter coil circuit corresponding tothe number of unit cells in the battery being tested.
 3. A batterytester, according to claim 1 in which said two shunt resistance meanscontains a fixed resistor, and variable resistance providing effectiveresistance value corresponding to the number of unit cells in thebattery being tested.
 4. A battery tester, as in claim 1, in which saidat least one scale of said indicating meter is divided into regionsindicating the battery being tested is adequate or inadequate for theservice for which the battery is being tested.